Bidet

ABSTRACT

An apparatus for washing human privates including a water heater ( 12 ), which is connected with a water supply pipe ( 8 ) and a hot water pipe ( 15 ) such that wash water supplied from the water supply pipe ( 8 ) is heated to a proper temperature by the water heater ( 12 ) while proceeding to the hot water pipe ( 15 ) through the water heater ( 12 ). A water supply controlling device ( 9, 10 ) controls the supply of wash water to the water heater ( 12 ). A discharge device ( 17 ) is provided for discharging to the human privates the wash water heated to the proper temperature by the water heater ( 12 ), which is connected with the hot water pipe ( 15 ). An air mixing device ( 21 ) is employed for mixing air into the wash water, and a controller ( 32 ) selectively controls the amount of air mixed into the wash water by the air mixing device ( 21 ).

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a human privates washing apparatus forwashing human bodies with hot water.

2. Description of Related Art

A conventional human privates washing apparatus of this kind is shown inFIG. 28 as disclosed in, for example, Japanese Patent Laid-OpenPublication No. 5-33377 (1993). FIG. 28 is a schematic view showing asupply system of wash water, in which a water supply pipe 152 isconnected with an upstream side of a pump 151 and an air mixing portion153 is mixed with a downstream side of the pump 151. The air mixingportion 153 includes a cylindrical suction head 154 made of ceramic suchthat air delivered from a compressor 155 is mixed into water in thesuction head 154. By this arrangement, wash water supplied from thewater supply pipe 152 is pressurized by the pump 151 and proceeds to theair mixing portion 153. In the air mixing portion 153, air supplied fromthe compressor 155 is divided into fine portions so as to flow into thewash water. Then, the wash water having passed through the air mixingportion 153 proceeds to a heat exchanger 156. The wash water heated to aproper temperature by the heat exchanger 156 is supplied to a nozzledevice 157 so as to be injected towards human privates. By thisfunction, the wash water injected from the nozzle device 157 containsair bubbles and thus, mild bodily sensation is obtained at the time ofwashing of the human privates.

However, in the above mentioned conventional human privates washingapparatus, control of the compressor 155 and control of the heatexchanger 156 are not associated with each other. Therefore, if ratio ofamount of the wash water to amount of air is not proper, a large amountof air is collected, thus resulting in local boiling or abnormal heatingin the heat exchanger 156. Meanwhile, since control of the compressor155 and control of the heat exchanger 156 are not integrated, a usershould perform a plurality of operations and cannot fully operate theconventional human privates washing apparatus unless the user is skilledin operational sequences or timings corresponding to situations.Furthermore, such a problem arises that any measure for reducing powerconsumption is not taken.

Meanwhile, since air bubbles are integrated with each other so as tobecome larger in diameter while proceeding from the air mixing portion153 to the nozzle device 157, hot wash water is injected intermittentlyfrom the nozzle device 157, thereby resulting in uncomfortable sensationduring use or scattering of the wash water. In addition, such aninconvenience is incurred that it is impossible to lessen heatingquantity through reduction of heat dissipation of the heat exchanger156.

Conventionally, generally known water heaters for human privates washingapparatuses are divided into a hot water storage type in which a fixedamount of water stored in a tank is at all times heated to and kept at aproper temperature by a heater and an instantaneous heating type inwhich supplied water is instantaneously heated such that hot waterheated to a proper temperature is fed. A hot water storage type waterheater is shown in FIG. 29 as disclosed in Japanese Patent PublicationNo. 2-3860 (1990). In FIG. 29, a lid 163 is securely fixed to an upperopen end of a hot water storage tank 161 of a water heater 162 by afastening member (not shown). A water inlet pipe 164 is attached to thelid 163. One end of the water inlet pipe 164 is connected with a watersupply source (not shown) via a water supply pipe 165, while the otherend of the water inlet pipe 164 extends through the lid 163 to avicinity of a bottom of the hot water storage tank 161. A hot waterdischarge portion 166 is attached to the lid 163 and has a hot wateroutlet 166a communicating with interior of the hot water storage tank161. A heater 167 for heating water is inserted into the hot waterstorage tank 161 through the lid 163. Meanwhile, a temperature sensor168 for detecting temperature of hot water is mounted on the lid 163such that a temperature sensing portion 168 a is inserted into the hotwater storage tank 161. Power supply to the heater 167 is controlled inaccordance with temperature of the hot water detected by the temperaturesensor 168 such that the hot water in the hot water storage tank 161 isat all times kept at a preset temperature of, for example, about 40° C.

However, in the conventional hot water storage type water heater of theabove described arrangement, since the amount of stored hot water islimited, hot water having the preset temperature is supplied until theamount of discharged water exceeds the amount of stored hot water.However, if this water heater is used for a such a long time that theamount of discharged water exceeds the amount of stored hot water,temperature of the hot water starts to drop gradually. Namely, if theamount of discharged water exceeds the amount of stored hot water, mostof the hot water heated by the heater 167 and stored in the hot waterstorage tank 161 is discharged from the hot water storage tank 161 andwater having flowed into the hot water storage tank 161 after start ofdischarge of the hot water is discharged. As a result, temperature ofthe hot water discharged from the hot water storage tank 161 starts todrop gradually. This happens because water having flowed into the hotwater storage tank 161 immediately after start of use of the hot wateris heated to vicinity of the preset temperature to some extent but waterhaving subsequently flowed into the hot water storage tank 161 isdischarged almost without being heated. Hence, since hot water having atemperature lower than the preset temperature is discharged, there is arisk that uncomfortable sensation is given to a user during washing ofthe body. Therefore, the hot water storage type water heater 162 hassuch a drawback that since the water heater 162 can be used only for acase in which period for discharging hot water is short, the human bodycannot be washed satisfactorily with hot water having the propertemperature unless washing period is shortened and the water heater 162is used intermittently.

In order to solve the above described problems in case the hot waterstorage tank 161 of the hot water storage type water heater 162 cannotbe made large, an instantaneous heating type water heater disclosed in,for example, Japanese Utility Model Publication No. 1-42757 (1989) asshown in FIG. 30 is adopted. A water heater 179 shown in FIG. 30 isconstituted by a metallic heating tank 180 formed into a cylindricalshape having a bottom and a hot water storage cylinder 181 formed into ahollow cylindrical shape. The heating tank 180 is accommodated in thehot water storage cylinder 181 such that a hot water storage portion 181a is defined above the heating tank 180. An open end of heating tank 180is fitted into one opening of the hot water storage cylinder 181 suchthat the heating tank 180 is communicated with the hot water storagecylinder 181 via a through-hole 182 formed on a peripheral edge of theheating tank 180 adjacent to the open end. Then, a hollow cylindricalceramic heater 183 including an electric heating element formed byperforming printing on its surface or between two ceramic substrates iscommunicated with a water supply line (not shown) so as to be looselyfitted thereinto. The opening of the hot water storage cylinder 181 isclosed by a flange of the ceramic heater 183. The other opening of thehot water storage cylinder 181 is closed by a housing 186 including afloat switch 184 and a vacuum switch 185 such that the housing 186 iscommunicated with the hot water storage cylinder 181. Thus, hot water isdischarged from a hot water discharge pipe 187 fixed to the housing 186.A temperature sensor 188 for detecting temperature of hot water heatedby the ceramic heater 183 is mounted above the through-hole 182 formedon the heating tank 180.

In the instantaneous heating type water heater 179, since waterproceeding through an inner periphery of the ceramic heater 183 into theheating tank 180 can be instantaneously heated to a preset temperatureby the electric heating element of the ceramic heater 183, namely, thewater flowing into the heating tank 180 can be continuously heated tothe preset temperature during flow of the water, hot water having afixed temperature can be continuously discharged for a long timeadvantageously. On the other hand, breakers for protecting overcurrentare installed on houses in general. In order to prevent trip of thebreakers, wattage of the heater should be set to be not more than about1200 W at AC 100 V. In case hot water having, for example, 40° C. isused, discharge rate should be not more than about 400 cc/min. in orderto raise temperature of water by 40 degrees in view of winter season inwhich temperature of water supplied to the water heater is low. In theinstantaneous heating type water heater of the above describedarrangement, as diameter of the hollow cylindrical ceramic heater 183 isreduced further, production of the ceramic heater 183 becomes moredifficult and its heat transfer area becomes smaller, so that there is alimit to diameter of the ceramic heater 183. Therefore, water storageportions in which water is collected are produced in water passages ofthe heating tank 180, the hot water storage cylinder 181, etc. whichhave volumes corresponding to size of the ceramic heater 183. Forexample, even if discharge rate is about 200 cc/min., its thermalcapacity becomes large due to the water storage portions and water iscollected in the water storage portions which are not so small as thedischarge rate of not more than about 400 cc/min. As a result, such adisadvantage is incurred that since not only a long time period isrequired for raising temperature and effecting response in temperaturecontrol but flow velocity becomes small due to large cross-sectionalareas of inner and outer peripheral flow paths of the ceramic heater 183as compared with the above discharge rate, heat transfer ratedeteriorates, thereby resulting in deterioration of thermal efficiencyof the water heater.

Meanwhile, in addition to the inconvenience that period for discharginghot water is limited, the human privates washing apparatus including theabove mentioned hot water storage type water heater has a drawback thatthe apparatus becomes large in size due to the hot water storage tankand a disadvantage that since power supply should be performed all daylong such that the apparatus can be used any time, loss caused by heatdissipation due to storage of hot water occupies a major portion ofwhole power consumption, thus resulting in extreme rise of its runningcost. On the other hand, the human privates washing apparatus includingthe instantaneous heating type water heater of the above describedarrangement has been disadvantageous in that since volume of the heatingtank becomes large due to size of the hollow cylindrical ceramic heater,it is difficult to make the apparatus compact and that since controlresponse is poor due to the water storage portions, it is difficult toinstantaneously change set temperature during washing.

In addition, conventionally, a flow rate sensor and a human privateswashing apparatus including the flow rate sensor are disclosed in, forexample, Japanese Patent Laid-Open Publication No. 6-264486 (1994) asshown in FIG. 31. The conventional flow rate sensor is described withreference to FIG. 31. FIG. 31 is a cutaway front elevational view of theflow rate sensor. In FIG. 31, a flow rate sensor 201 is constituted by abody 204 having an inflow path 202 and an outflow path 203, an impeller206 rotatably supported by a shaft 205 mounted on the body 204 and aphoto interrupter 207. The photo interrupter 207 is disposed at such aposition that its optical axis passes through a peripheral edge of aside plate 208 provided on the impeller 206. Light is intercepted by theside plate 208 but passes through a plurality of recesses 209 formed ona peripheral edge of the side plate 208 at regular intervals such thatthe number of revolutions of the impeller 206 is detected.

Meanwhile, FIG. 32 is a piping diagram of a human privates washingapparatus including this flow rate sensor. In FIG. 32, a hot waterstorage tank 212 incorporating a heater 211 is connected with adownstream side of a water supply pump 210. Meanwhile, a washing nozzle213 for injecting wash water to human privates is connected with adownstream side of the hot water storage tank 212 through a flow ratesensor 201. On the basis of flow rate expressed by the number ofrevolutions of the impeller 206 and its variations delivered from theflow rate sensor 201, a controller 214 controls drive voltage of thewater supply pump 210.

However, in the known flow rate sensor of FIG. 31, since wash water forrotating the impeller 206 flows rectilinearly from the inflow path 202to the outflow path 203, fluidal force for rotating the impeller 206 isinsufficient. Therefore, at the time of low flow rate, the impeller 206is likely to be not rotated or be rotated unstably disadvantageously.Meanwhile, if air bubbles have adhered to the impeller 206 in some formor other, the air bubbles are integrated in the vicinity of a rotarycenter of the impeller 206 by centrifugal force produced by rotation ofthe impeller 206, so that such problems arise that it is difficult todischarge the air bubbles outwardly and rotations of the impeller 206become unstable, thereby resulting in drop of accuracy of detection offlow rate.

Meanwhile, in the conventional human privates washing apparatus of FIG.32, since power supply to the heater 211 should be performed at alltimes in order to maintain temperature of wash water in the hot waterstorage tank 212, loss of power consumption is caused by heatdissipation. In addition, since air dissolved in the wash water in thehot water storage tank 212 is likely to appear as air bubbles uponheating and the air bubbles flow into the flow rate sensor 201, a largeerror is produced in value of detected flow rate due also to the abovedescribed problems.

SUMMARY OF THE INVENTION

Accordingly, the present invention has for its object to provide, with aview to eliminating the above mentioned drawbacks of prior art humanprivates washing apparatus, a human privates washing apparatus in whichan amount of air mixed into wash water is changed in response to controlof the flow rate of the wash water such that air is prevented fromremaining in a heating means or a hot water pipe due to an impropermixing ratio of air. In the present invention, a user need not perform aplurality of operations, and an instantaneous heating means is employedso as to reduce loss due to heat dissipation and the amount of washwater is reduced by mixing of air thereinto such that power consumptionis lessened greatly.

In order to accomplish this object, a human privates washing apparatusaccording to the present invention comprises: a water heater which isconnected with a water supply pipe and a hot water pipe such that washwater supplied from the water supply pipe is heated to a propertemperature by the water heater while proceeding to the hot water pipethrough the water heater; a water supply controlling means forcontrolling supply of the wash water to the water heater; a dischargemeans for discharging to the human privates the wash water heated to theproper temperature by the water heater, which is connected with the hotwater pipe; an air mixing means for mixing air into the wash water; anda controller for controlling so as to change, in response to control ofthe supply of the wash water by the water supply controlling means,amount of the air mixed into the wash water by the air mixing means.

In the human privates washing apparatus of the present invention, sincethe air mixing means is provided between the water heater and thedischarge means, air bubbles are prevented from remaining in the waterheater and becoming larger in diameter. Meanwhile, since the waterheater is of instantaneous heating type, power consumption is lessenedby reducing loss due to heat dissipation and amount of hot water bymixing of air thereinto.

Meanwhile, in order to eliminate the above described disadvantages ofconventional water heaters for human privates washing apparatuses, thepresent invention provides a water heater for a human privates washingapparatus includes a flat platelike heating means, a water inlet, a hotwater outlet and an internal flow path which is communicated with thewater inlet and the hot water outlet, has at least one bent portion andis disposed in thermal contact with each of opposite faces of theheating means.

In the water heater for the human privates washing apparatus, accordingto the present invention, since flow velocity can be increased whileheat transfer area is secured, heat transfer rate can be increased, sothat the water heater can be made for higher load and more compact.

Furthermore, in order to solve the above described problems of knownflow rate detecting means for human privates washing apparatuses, thepresent invention provides a flow rate detecting means for a humanprivates washing apparatus comprises: a rotor which includes a pluralityof rotary vanes extending radially from its axis at regular angularintervals and having an identical shape; a housing which has asubstantially cylindrical chamber for receiving the rotor; an inflowpath which causes the wash water to flow into the chamber in atangential direction of a rotational circle of the rotor; an outflowpath which is provided at such a position that a streamline drawn by thewash water flowing into the chamber from the inflow path defines asubstantially U-shaped locus along the rotational circle of the rotor;and a detection means for detecting the number of revolutions of therotor.

In the flow rate detecting means for the human privates detectingapparatus, since large fluidal force is applied to the rotor during itsrotations, stable output can be obtained even by quite minute flow rateand thus, value of detected flow rate is improved.

Meanwhile, in the flow rate detecting means for the human privatesdetecting apparatus, if the outflow path is formed inwardly of an outerperiphery of the rotor and in parallel with the axis of the rotor, airbubbles adhering to the rotor are readily discharged from the outflowpath without being collected in the vicinity of the axis of the rotor,so that rotational nonuniformity of the rotor and improper detection ofthe detection means for detecting the number of revolutions of the rotorare prevented, thereby resulting in improvement of accuracy of detectionof flow rate.

These objects and features of the present invention will become clearfrom the following description taken in conjunction with the preferredembodiments thereof with reference to the accompanying drawingsthroughout which like parts are designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram of a human privates washing apparatusaccording to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view explanatory of a main arrangementof a water heater employed in the human privates washing apparatus ofFIG. 1.

FIG. 3 is a top plan view of a washing nozzle employed in the humanprivates washing apparatus of FIG. 1.

FIG. 4 is partial sectional side elevational view of the washing nozzleof FIG. 3.

FIG. 5 is a fragmentary sectional view of an air detecting thermistoremployed in the human privates washing apparatus of FIG. 1.

FIG. 6 is a flow chart showing control of operation of the humanprivates washing apparatus of FIG. 1.

FIG. 7 is a graph showing the relation between the amount of wash waterand air mixing ratio in the human privates washing apparatus of FIG. 1.

FIG. 8 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a second embodiment of thepresent invention.

FIG. 9 is a transverse sectional view of the water heater of FIG. 8.

FIG. 10 is a longitudinal sectional view of the water heater of FIG. 8.

FIG. 11 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a third embodiment of thepresent invention.

FIG. 12 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a fourth embodiment of thepresent invention.

FIG. 13 is a horizontal sectional view of the water heater of FIG. 12.

FIG. 14 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a fifth embodiment of thepresent invention.

FIG. 15 is a transverse sectional view of the water heater of FIG. 14.

FIG. 16 is a longitudinal sectional view of the water heater of FIG. 14.

FIG. 17 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a sixth embodiment of thepresent invention.

FIG. 18 is a horizontal sectional view of the water heater of FIG. 17.

FIG. 19 is a vertical sectional view of the water heater of FIG. 17.

FIG. 20 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a seventh embodiment ofthe present invention.

FIG. 21 is a schematic view showing an arrangement of the water heaterof FIG. 20.

FIG. 22 is an enlarged fragmentary sectional view of a water heateremployed in a human privates washing apparatus according to an eighthembodiment of the present invention.

FIG. 23 is an enlarged fragmentary sectional view of a water heateremployed in a human privates washing apparatus according to a ninthembodiment of the present invention.

FIG. 24 is a sectional view of a flow rate sensor employed in a humanprivates washing apparatus according to a tenth embodiment of thepresent invention.

FIG. 25 is a front elevational view of the flow rate sensor of FIG. 24.

FIG. 26 is a sectional view of a flow rate sensor employed in a humanprivates washing apparatus according to an eleventh embodiment of thepresent invention.

FIG. 27 is a front elevational view of the flow rate sensor of FIG. 26.

FIG. 28 is a system diagram of a prior art human privates washingapparatus.

FIG. 29 is a schematic sectional view of a further prior art humanprivates washing apparatus.

FIG. 30 is a schematic sectional view of a still further prior art humanprivates washing apparatus.

FIG. 31 is a partially cutaway front elevational view of a conventionalflow rate sensor.

FIG. 32 is a schematic view showing an arrangement of a conventionalhuman privates washing apparatus employing the flow rate sensor of FIG.31.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention aredescribed with reference to the attached drawings.

(First Embodiment)

FIG. 1 shows a human privates washing apparatus according to a firstembodiment of the present invention. In FIG. 1, water supplied from awater supply pipe 8 proceeds to an instantaneous heating type waterheater 12 (i.e., a heating means which is capable of continuouslyheating the water to a preset temperature during flow of the water asdescribed earlier in “Background Art”) through a main solenoid valve 9,a motor-driven flow control valve 10 for adjusting amount of wash waterand a flow rate sensor 11 acting as a flow detecting means for detectingflow and flow rate of wash water. The main solenoid valve 9 and the flowcontrol valve 10 each act as a water supply controlling means. The waterheater 12 is provided with a high limit switch 13 for directly cuttingoff power supply to the water heater 12 upon detection of abnormal riseof temperature of the water heater 12 itself and an air detectingthermistor 14 for detecting presence or absence of water in the waterheater 12. A hot water thermistor 16 for detecting temperature of hotwater is provided on a hot water pipe 15 disposed adjacent to an outletof the water heater 12. A washing nozzle unit 18 at a distal end ofwhich a washing nozzle 17 acting as a discharge means is provided isconnected with a distal end of the hot water pipe 15. Projection andretraction of the washing nozzle 17 are controlled by a motor. Betweenthe washing nozzle 17 and the water heater 12, air is mixed into washwater through an air pipe 20 by a motor-driven air pump 21 acting as anair mixing means. Wash water fed from the washing nozzle 17 is used forwashing privates of a user seated on a toilet seat 22. The toilet seat22 is provided with a seating switch 23 for detecting seating of theuser on the toilet seat 22.

A command for effecting feed of wash water from the washing nozzle 17 isissued from a remote control unit 24. The remote control unit 24 has ananal washing switch 25, a bidet washing switch 26 for washing femalegenitals, a stop switch 27 for stopping wash water, an adjustmentportion 28 for adjusting flow rate and temperature of wash water and achangeover switch 29 for changing over adjustment of the adjustmentportion 28 to flow rate or temperature of wash water. The anal washingswitch 25 and the bidet washing switch 26 each act as a washing settingmeans and a selection means, while the stop switch 27 acts as thewashing setting means and acts also as a flow rate detecting means forindirectly detecting stop of flow of wash water. Meanwhile, in FIG. 1,only the washing nozzle unit 18 for anal washing is illustrated and awashing nozzle unit for bidet washing having a similar arrangement isprovided but is not illustrated.

Meanwhile, a controller 32 receives radio signals from the remotecontrol unit 24 and controls the respective constituent elementsconnected with the controller 32 as shown by dot lines. The controller32 has an air mixing ratio controller 30 for controlling mixing ratio ofair to wash water and a flow rate controller 31 for effecting control onthe basis of signals from flow rate sensor 11. The controller 32 isprovided with a preheating switch 33 for selecting heating in the waterheater 12 when water or hot water does not flow.

FIG. 2 shows details of the water heater 12. A ceramic heater 34 forperforming heating electrically is gripped between copper plates 35 and36 and resinous casings 38 and 39 each having an internal flow path areprovided outside the copper plates 35 and 36. These casings 38 and 39are pressed against the copper plates 35 and 36 by sealing mediums 40.Meanwhile, the high limit switch 13 is attached to a surface of thecopper plate 35, while the air detecting thermistor 14 is fixed to anupper portion of the casing 38.

FIGS. 3 and 4 show details of the washing nozzle 17. FIG. 3 is a topplan view showing the washing nozzle 17 observed from above and FIG. 4is a partly sectional side elevational view of the washing nozzle 17. Aflow path in the washing nozzle 17 is gradually reduced incross-sectional area from a flow path 41 of the washing nozzle unit 18to flow paths 42 and 43 in the washing nozzle 17 and then, extends via aparallel portion 45 to an enlarged portion 46 having a width increasinggradually towards a nozzle port 44. By this arrangement, when hot waterhaving air mixed thereinto is fed, wash water is discharged to humanprivates while being swung in a comparatively wide range by a functionof air mixing and a function of the enlarged portion 46. Namely, Coandaphenomenon in which when proceeding from the parallel portion 45 to theenlarged portion 46, hot water adheres to one of its opposed walls isdisturbed by air mixed into the hot water at random, so that a jet isfed so as to be swung laterally. When mixing of air into hot water isstopped, hot water is rectilinearly discharged in a comparatively narrowrange by a function of the parallel portion 45. By selecting whether ornot air is mixed into hot water through utilization of this phenomenon,the washing jet can be fed through changeover between swing motion andrectilinear motion.

FIG. 5 shows details of the air detecting thermistor 14. A periphery ofa bead 47 of the thermistor is protected by a protective pipe 48 andfiller 49 is filled between the bead 47 and the protective pipe 48 so asto be packed. The protective pipe 48 is fixed by a clamp so as toproject into a flow path of the hot water pipe 15. An air detectingprinciple in this air detecting thermistor 14 is as follows. Initially,after temperature has been measured preliminarily, electric power issupplied to the air detecting thermistor 14 itself so as to heat the airdetecting thermistor 14. Upon lapse of a predetermined period,temperature is measured again and is compared with the temperaturemeasured prior to heating. In case the air detecting thermistor 14 issurrounded by water (hot water), heat dissipation after heating iscomparatively large and thus, temperature difference between prior toand after heating is small. If the air detecting thermistor 14 issurrounded by air, heat dissipation after heating is comparatively smalland thus, temperature difference between prior to and after heating islarge. On the basis of magnitude of this temperature difference, it isjudged whether the air detecting thermistor 14 is surrounded by water(hot water) or air. In order to form an accurate judgement in a seriesof this control, heating period is set to be long and short whentemperature prior to heating is high and low, respectively. Meanwhile, adecision as to whether the air detecting thermistor 14 is surrounded bywater or air is made on the basis of difference between temperatureprior to heating and temperature after heating so as to be less affectedby ambient temperature.

Operation of the human privates washing apparatus of this embodiment isdescribed with reference to FIG. 6. When a power source has been turnedon at step S1 and the anal washing switch 25 has been operated at stepS2, the program flow proceeds to step S4 of temperature decision of thehot water thermistor 16 if the seating switch is in ON state throughseating of the toilet seat 22 by the user at step S3. The controller 32judges that it is safe and dangerous when temperature detected by thehot water thermistor 16 is less than and not less than a predeterminedtemperature of 50° C., respectively. In case it is judged that it isdangerous, subsequent discharge of wash water to human privates is notperformed. By this judgement, discharge of high-temperature hot water tothe human privates from the washing nozzle 17 is prevented and thus,safety against any possible danger is ensured. Meanwhile, also duringuse, if temperature of hot water is not less than 50° C. due to failureof a temperature control system of the water heater 12 or sudden drop ofamount of wash water, the hot water thermistor 16 detect this andimmediately stops supply of hot water by the main solenoid valve 9.Subsequently, the air pump 21 is started at step S5, the main solenoidvalve 9 is opened at step S6 and the washing nozzle 17 is graduallyprojected at step S7. The air pump 21 is started earlier in order toprevent back flow of water even if a check mechanism of the air pump 21itself fails. By this function, it is possible to prevent deteriorationof performance and failure due to back flow of water or hot water intothe air pump at the time of start of use.

Then, after a while, value of the flow rate sensor 11 is read at steps8. If flow rate exceeds 0.2 l/min. at step S9, the controller 32 judgesthat there is flow of water, so that power supply to the water heater 12is started such that wash water is heated by producing heat from theceramic heater 34 at step S10. Thereafter, a flow rate value set at theremote control unit 24 is read at step S11 and the flow control valve 10is controlled by comparing this set value with a value detected by theflow rate sensor 11 so as to obtain flow rate of the set value at stepS12.

Then, voltage applied to the air pump 21 is controlled on the basis ofthe read value of the flow rate sensor 11 such that a ratio of amount ofair mixed into wash water to a preset amount of wash water assumes apredetermined value at step S13. The number of revolutions of a motor ofthe air pump 21, hence, amount of air discharged from the air pump 21changes according to voltage. Relation between amount of wash water andamount of air mixed thereinto is shown in FIG. 7. In the case of analwashing, air mixing ratio is increased as amount of wash water isreduced. If air mixing ratio is increased, diameter of air bubbles isapt to increase as amount of wash water is reduced, for the followingreason. Namely, flow rate of wash water is restricted at its inlet bythe flow control valve 10. Therefore, if flow rate of wash water isreduced, internal pressure of wash water at the washing nozzle 17 drops,so that diameter of air bubbles is likely to become larger even if thesame amount of air as that for large amount of wash water is mixed intowash water.

Generally, if amount of air bubbles having large diameter is increased,stimulative bodily sensation is increased and washing capability is alsoupgraded. However, if amount of air bubbles is increased extremely, jetis inclined to become intermittent, which is disliked by many users. Inview of this in anal washing, priority is given to washing capabilityand control is performed such that air mixing ratio is properlyincreased as amount of wash water is reduced. Meanwhile, in bidetwashing, if air mixing ratio is raised, diameter of air bubblesincreases, which gives disgustful bodily sensation to many users. Inbidet washing, many users are inclined to estimate sensation thatprivates are wetted higher than washing effect of wash water itself.Therefore, in bidet washing, control is performed such that air mixingratio is lessened as amount of wash water is reduced. At any rate, sinceamount of air mixed into wash water can be changed automatically inresponse to control of flow rate of wash water, the user need notperform a plurality of operations and need not be skilled in operationalsequences or timings corresponding to situations, so that even the oldor children can use the apparatus at will.

Thereafter, in order to obtain a desired temperature of wash water, thecontroller 32 compares a temperature set at the remote control unit 24with a temperature of the hot water thermistor 16 so as to adjustquantity of heating of the water heater 12 at step S14. In case the settemperature of wash water is to be changed, the changeover switch 29 foreffecting changeover between flow rate and temperature in the remotecontrol unit 24 is changed over to temperature such that temperature isadjusted at the adjustment portion 28. Meanwhile, in case the set flowrate is to be changed, the changeover switch 29 is changed over to flowrate such that flow rate is adjusted at the adjustment portion 28. Ifthe set flow rate is changed, amount of air mixed into wash water ischanged in response to flow rate of wash water as described above.Accordingly, such malfunctions can be prevented that temperature of theceramic heater 34 is raised abnormally due to back flow of air into thewater heater 12 caused by extreme reduction of amount of. air and washwater flows backwardly into the air pump 21 due to lack of rotations ofthe air pump 21. Meanwhile, bodily sensation and washing capability canbe made proper and the user can use the apparatus precisely withoutperforming a plurality of operations.

Hot water which has been adjusted to the set flow rate by the flowcontrol valve 10 and adjusted to the set temperature by the water heater12 proceeds to the washing nozzle unit 18. At the washing nozzle unit18, the hot water is mixed with air supplied through the air pipe 20from the air pump 21 and then, is discharged to the human privates fromthe washing nozzle 17. In the case of washing of the human privates withhot water mixed with air, wash water is swung over a comparatively widearea of the human privates by function of the washing nozzle 17 so as towash the human privates. In comparison with a conventional case in whichwashing is performed with only hot water, washing can be performed at aflow rate not more than a half of that of the conventional case withoutincurring deterioration of washing capability and the user's bodilysensation. This has been confirmed also experimentally.

Meanwhile, since the instantaneous heating type water heater 12 isemployed, loss due to heat dissipation during storage of hot water in aconventional hot water storage type heating means is eliminated, so thatpower consumption may be about a half of that of the conventionalheating means. By also the feature that the flow rate may be the half ofthat of the conventional case, power consumption can be reduced greatly.If a season having low temperature of supplied water is taken intoconsideration, an instantaneous heating type water heater generallyrequires a rated value of about 2.5 KW (25 A) and utilization of thewater heater has been difficult due to the restriction that general plugreceptacles for home use are limited to 15 A. However, in the presentinvention, since the water heater 12 may require only 1.2 KW, thegeneral plug receptacles can be used. Meanwhile, since the air pump 21for mixing air into hot water is provided between the water heater 12and the washing nozzle 17, it becomes possible to prevent air fromremaining in the water heater 12 and thus, local boiling and abnormalheating in the water heater 12 can be prevented.

Heating of wash water by the water heater 12 and mixing of air by theair pump 21 are continued until the stop switch 27 is operated at stepS15. In case a stop command is issued by operating the stop switch 27,power supply to the water heater 12 is initially stopped so as to cut off power supply to the ceramic heater 34 at step S16. In this stopoperation, power supply to the ceramic heater 34 is cut off inaccordance with the stop command of the stop switch 27 before the flowrate sensor 11 reaches not more than a predetermined stop value of 0.18l/min., so that safety is ensured. Namely, at the time of start of flow,the controller 32 starts power supply by detecting that a signal fromthe flow rate sensor 11 has exceeded the predetermined value. Meanwhile,at the time of stop of flow, the controller 32 stops power supply bydetecting that the stop switch 27 has been pushed. As a result, thecontroller 32 secures safety not only by starting power supply afterwater has positively flown into the ceramic heater 34 but by stoppingpower supply before flow of water stops. In this case, the stop switch27 functions as an indirect flow rate detecting means. In addition, incomparison with a case in which power supply to the ceramic heater 34 isstopped in response to the signal from the flow rate sensor 11, theceramic heater 34 can be stopped earlier and temperature rise due tolate heating caused by residual heat can be lessened by also the effectthat flow is stopped subsequently.

Subsequently, after late heating caused by residual heat has beenprevented by causing water to flow through the water heater 12 for apredetermined period, the main solenoid valve 9 is stopped at step S17.Then, when the flow rate sensor 11 detects that supply of wash water tothe washing nozzle unit 18 has been stopped and the washing nozzle unit18 has lost washing capability, the washing nozzle 17 is retracted atstep S18. After the main solenoid valve 9 has been stopped, the air pump21 is operated for a predetermined period so as to dischargehigh-temperature hot water produced by late heating caused by residualheat and then, the air pump 21 is stopped at step S19. In case flow ofwater has been stopped during use due to delivery of water mixed with alarge amount of air or suspension of water supply, the flow rate sensor11 detects that flow rate has reached not more than 0.18 l/min., so thatpower supply to the ceramic heater 34 is terminated such that heatingperformed without water and abnormal rise of temperature are prevented.Meanwhile, in case temperature of hot water rises due to failure of thecontroller 32, the high limit switch 13 set at 60° C. functions to turnoff a main power source of the normal closed type main solenoid valve 9so as to close the main solenoid valve 9 such that supply of hot wateris stopped.

In case the water heater 12 is preheated when supply of hot water is notbeing performed, presence or absence of air in the water heater 12 isinitially detected by the air detecting thermistor 14. If the airdetecting thermistor 14 is surrounded by air, power supply to the waterheater 12 is not performed when water supply to the water heater 12 isnot being performed. Meanwhile, also when the preheating switch 33 isnot turned on, preheating of the water heater 12 by the ceramic heater34 is not performed. Preheating is performed until temperature detectedby the hot water thermistor 16 reaches the predetermined temperature of40° C. such that rapid rise of temperature is effected at the time ofreoperation.

Supply and stop of hot water upon push of the bidet washing switch 26are performed in the same manner as those of anal washing referred toabove and thus, the description is abbreviated. As described earlier,bidet washing is characterized in that air mixing ratio is controlled soas to be reduced as amount of wash water is reduced.

In this embodiment, the water heater 12 including the ceramic heater 34is employed as an instantaneous heating type heating means by way ofexample. The heater may also be replaced by other electrical heatingmeans such as a sheathed heater and a heater in which a ribbon heater isinsulated by mica. Meanwhile, heat of combustion may be utilized insteadof electrical heating.

Meanwhile, the hot water thermistor 16 provided in the vicinity of theoutlet of the water heater 12 is recited as a temperature detectingmeans in the vicinity of the heating means by way of example. Thetemperature detecting means may be provided in an internal flow path ofthe water heater 12 or may be mounted on the copper plate 35 or 36.Meanwhile, in addition to the thermistor, any other temperaturedetecting means such as a thermocouple and a metallic resistor can beemployed.

Meanwhile, the main solenoid valve 9 and the flow control valve 10 areemployed as the water supply controlling means by way of example but anindependently provided main solenoid valve, an independently providedflow control valve having a water stop function or a water pump may actas the water supply controlling means.

Meanwhile, the washing nozzle 17 in which hot water is swung upon mixingof air thereinto is employed as the discharge means by way of examplebut a type in which hot water is not swung or a shower for merelydischarging hot water mixed with air may act as the discharge means.

Meanwhile, the air pump 21 is employed as the air mixing means but maybe replaced by a compressor, a blower or compressed air feeders providedat a remote location in a concentrated manner.

Meanwhile, the flow rate sensor 11 for directly detecting flow rate isemployed as the flow rate detecting means by way of example but may bereplaced by an indirect flow rate detecting means which detects a signalon opening degree of a flow control valve or the number of revolutionsof a water supply pump.

Meanwhile, the flow rate sensor 11 for directly detecting flow of waterand the stop switch 27 for indirectly detecting flow of water areemployed as the flow rate detecting means for detecting flow of water orhot water by way of example but other indirect flow rate detecting meanssuch as a flow rate switch or a pressure switch may act as the flow ratedetecting means.

The air detecting thermistor 14 is employed as an air detecting means byway of example but may be replaced by a method in which water level isdetected by an electrode or a float, a method in which composition ofair is detected and a method in which presence of air is detectedoptically.

The stop switch 27, the anal washing switch 25 and the bidet washingswitch 26 provided on the remote control unit 24 are employed as thewashing setting means by way of example but an on-off valve for directlyopening and closing the flow path of the water supply pipe and the hotwater pipe may act as the washing setting means.

Meanwhile, the anal washing switch 25 and the bidet washing switch 26are employed as the selection means by way of example but the selectionmeans may be arranged to enable arbitrary selection of air mixing ratiofor an identical site of the privates in accordance with diseases orhealth conditions without selecting sites of the privates.

(Second Embodiment)

FIGS. 8, 9 and 10 are a schematic perspective view, a transversesectional view and a longitudinal sectional view of a water heateremployed in a human privates washing apparatus according to a secondembodiment of the present invention, respectively. In FIGS. 8 to 10, awater heater body 61 is constituted by a ceramic heater 62 acting as aflat platelike heating means and provided at its substantially centralportion and a pair of metallic heat exchange portions 64. Silicone agent63 is applied to one face of the heat exchange portion 64 brought intocontact with the ceramic heater 62 so as to improve heat conductiontherebetween such that the ceramic heater 62 is gripped between the heatexchange portions 64. In the ceramic heater 62, a metallic heatingelement 65 which produces Joule's heat by supplying electric powerthereto is gripped between a pair of rectangular ceramic plates 66 madeof alumina or the like and then, is calcined integrally. Lead wires 67are connected with opposite ends of the heating element 65. Meanwhile,in each of the heat exchange portions 64, a meandering water passage 69having a plurality of bent portions 68 is formed in a substantiallycentral cross section parallel to the ceramic heater 62 and iscommunicated with a water inlet 70 and a hot water outlet 71 opening toone end surface of each of the heat exchange portions 64. The hot wateroutlet 71 of one heat exchange portion 64 is connected with the waterinlet 70 of the other heat exchange portion 64 by a pipe 72.

By the above described arrangement, when water is introduced into thewater inlet 70 of the one heat exchange portion 64 and electric power issupplied to the ceramic heater 62 from the lead wires 67, heat producedby the heating element 65 is conducted to the heat exchange portions 64through the ceramic plates 66 and the silicone agent 63 so as to betransferred to water having flowed into the water heater from the waterinlet 70. Since the water is heated while flowing in series from themeandering water passage 69 of the one heat exchange portion 64 to themeandering water passage 69 of the other heat exchange portion 64 viathe pipe 72, the water is turned into hot water in a short period duringwhich the water passes through the water heater body 61, so that the hotwater is discharged from the hot water outlet 71.

Therefore, since the water heater body 61 is an instantaneous heatingtype water heater in which water supplied continuously from the waterinlet 70 is heated instantaneously, hot water having a fixed temperaturecan be discharged uninterruptedly for a long time. Meanwhile, since awall of the meandering water passage 69 is a heat transfer surface, alarge heat transfer area can be secured along a length of the wall andflow velocity can be increased by reducing cross-sectional area of themeandering water passage 69, so that its heat transfer rate can beincreased. Thus, the water heater can be made for higher load and morecompact in a simple construction at high thermal efficiency.Furthermore, since there is no water storage portion, thermal capacityof water is minute, so that temperature raise speed from start of use ofthe water heater to actual discharge of hot water having propertemperature is high and thus, control response is also improved in casea controller is provided so as to enable a user to change temperature orflow rate of hot water, etc.

Meanwhile, in this embodiment, the flat platelike ceramic heater isemployed as the flat platelike heating means but may be modifiedvariously, for example, a sheathed heater and a mica heater.

(Third Embodiment)

FIG. 11 is a schematic perspective view of a water heater employed in ahuman privates washing apparatus according to a third embodiment of thepresent invention. Constituent elements having reference numeralsidentical with those of FIG. 8 to 10 correspond to the constituentelements of FIGS. 8 to 10 and therefore, the detailed description isabbreviated. In FIG. 11, a pair of the heat exchange portions 64 aremade of resinous material and the meandering water passage 69 opens toone face of each of the heat exchange portions 64 adjacent to theceramic heater 62 such that water comes into direct contact with theceramic heater 62. An O-ring 73 is provided in each of the heat exchangeportions 64 so as to close the meandering water passage 69 such thatwater does not leak from the meandering water passage 69.

By the above described arrangement, when water is introduced into thewater inlet 70 and electric power is supplied to the ceramic heater 62,the ceramic heater 62 is formed by alumina which is an electricalinsulator and has a large thermal conductivity, temperature raise speedof the heating means itself is high. As a result, since temperatureraise and temperature control response of hot water can be performed ina moment and water having flowed into the water heater from the waterinlet 70 is brought into direct contact with the ceramic heater 62 inthe meandering water passage 69. Therefore, temperature raise speed andresponse can be further improved and thermal efficiency also can beraised. At this time, since water is electrically insulated from theheating element 65, the water heater can be operated without a risk ofleak or short circuit.

(Fourth Embodiment)

FIGS. 12 and 13 are a schematic perspective view and a horizontalsectional view of a water heater employed in a human privates washingapparatus according to a fourth embodiment of the present invention,respectively. Constituent elements having reference numerals identicalwith those of FIGS. 8 to 11 correspond to the constituent elements ofFIGS. 8 to 11 and therefore, the detailed description is abbreviated. InFIGS. 12 and 13, a catalytic combustion burner 74 is provided as a flatplatelike heating means and is constituted by a fuel pipe 75 forsupplying hydrocarbon fuel such as propane, butane and methanol, avolume portion 76 for causing uniform flow of the fuel supplied from thefuel pipe 75, a flat fuel passage 78 including two metal plates 77 bentlike a corrugated plate and extending upwardly in platelike manner fromthe volume portion 76 disposed at a lower portion of the catalyticcombustion burner 74, catalytic combustion portions 79 each formed byapplying catalyst (not shown) to each of the metal plates 77 and anexhaust vent 80 for discharging exhaust combustion gas. A pair of themetallic heat exchange portions 64 are, respectively, bonded to oppositesides of the fuel passage 78 so as to readily transfer heat to the fuelpassage 78 and thus, the water heater is obtained.

By the above described arrangement, fuel supplied from the fuel pipe 75enters, via the volume portion 76, the fuel passage 78 gripped between apair of the heat exchange portions 64. The fuel having entered the fuelpassage 78 is brought into contact with the catalytic combustionportions 79 while passing through a gap between the metal plates 77 andproduces heat through oxidation reaction with oxygen in air under actionof the catalyst so as to be discharged, as exhaust combustion gas, fromthe exhaust vent 80. Heat produced at the catalytic combustion portion79 at this time is conducted to the heat exchange portions 64 by way ofthe metal plates 77 and wall surfaces of the fuel passage 78 and istransferred to water introduced into the water heater from the waterinlet 70 while the water is flowing through the meandering water passage69 formed at the substantially central portion of each of the heatexchange portions 64, so that the water is turned into hot water havingproper temperature such that the hot water is discharged from the hotwater outlet 71. Consequently, it is possible to materialize aninstantaneous heating type compact water heater having a simpleconstruction, in which fuel such as hydrocarbon fuel is used. Meanwhile,since catalytic combustion is utilized, oxidation reaction progresseswithout reaching excessively high temperature, so that nitrogen oxides,etc. are not produced at high temperature and thus, the water heateremits clean exhaust gas.

(Fifth Embodiment)

FIGS. 14, 15 and 16 are a schematic perspective view, a transversesectional view and a longitudinal sectional view of a water heateremployed in a human privates washing apparatus according to a fifthembodiment of the present invention, respectively. Constituent elementshaving reference numerals identical with those of FIGS. 8 to 13correspond to the constituent elements of FIGS. 8 to 13 and therefore,the detailed description is abbreviated. In the drawings, a water supplysource (not shown) and the respective water inlets 70 of a pair of theresinous heat exchange portions 64 are connected with a water supplypipe 82 having a branch portion 81, while the two hot water outlets 71are connected with a hot water discharge pipe 84 having a confluentportion 83. In each of the heat exchange portions 64, the water inlet 70and the hot water outlet 71 are provided adjacent to each other and themeandering water passage 69 communicating with the water inlet 70 andthe hot water outlet 71 opens to one face of the heat exchange portion64 adjacent to the ceramic heater 62, while an inflow path 85 close tothe water inlet 70 and an outflow path 86 close to the hot water outlet71 proceed next to and in parallel with each other and then, areconnected with each other through the bent portions 68. A copper plate87 acting as a heat transfer plate is integrally fixed to the heatexchange portion 64 through the O-ring 73 so as to close this openmeandering water passage 69 such that leakage of water from themeandering water passage 69 does not occur. A pair of the heat exchangeportions 87 each provided integrally with the copper plate 87 arebrought into pressing contact, through a thin rubber sheet 88 having anexcellent thermal conductivity, with the ceramic heater 62 smaller inarea than the meandering water passage 69.

By the above described arrangement, water supplied to the water supplypipe 82 is caused to branch off from the branch portion 81 substantiallyequally so as to flow into the two water inlets 70. The water is heatedto hot water by the ceramic heater 62 while passing through the inflowpath 85 and a plurality of the bent portions 68. Since this hot waterperforms heat exchange with also water in the inflow path 85 lying nextto the outflow path 86 of the meandering water passage 69,low-temperature water having entered the meandering water passage 69 isheated rapidly and thus, temperature difference in the meandering waterpassage 69 is lessened. The copper plate 87 having a large thermalconductivity further reduces this lessened temperature difference in themeandering water passage 69 through diffusion of heat a cross-sectionaldirection of the copper plate 87. As a result, since distribution oftemperature on surfaces of the ceramic heater 62 becomes uniform,fracture of the ceramic heater 62 due to thermal strain can beprevented. Even when the heating element 65 acting as a heating portionof the ceramic heater 62 is formed up to an edge of the ceramic heater62, the meandering water passage 69 is formed in an area larger thanthat of the heating element 65 so as to cover the ceramic heater 62.Therefore, since heat flow is transmitted to the constituent elements ofthe water heater such as the heat exchange portions 64 without beingabsorbed by water, it is possible to prevent an end portion, etc. of thewater heater from partially reaching abnormally high temperature,thereby resulting in improvement of thermal efficiency and safety. Inaddition, since supplied water is caused to branch off from the branchportion 81 of the water supply water can be fed to a pair of the heatexchange portions 64 substantially equally, so that thermal conditionsof opposite faces of the ceramic heater 62 become identical with eachother. Hence, since temperature gradient is not produced between theopposite faces of the ceramic heater 62, fracture of the ceramic heater62 due to thermal strain can be prevented, thus resulting in improvementof reliability. Meanwhile, in case the catalytic combustion burner 74made of metal is employed as the flat platelike heating means as shownin FIG. 12, the heating means is subjected to warpage due to thermalstrain, which also can be prevented in this embodiment.

(Sixth Embodiment)

FIGS. 17, 18 and 19 are a schematic perspective view, a horizontalsectional view and a vertical sectional view of a water heater employedin a human privates washing apparatus according to a sixth embodiment ofthe present invention, respectively. Constituent elements havingreference numerals identical with those of FIGS. 8 to 16 correspond tothe constituent elements of FIGS. 8 to 16 and therefore, the detaileddescription is abbreviated. In the drawings, the water heater body 61 isconstituted by one resinous heat exchange portion 64 having one waterinlet 70 and one hot water outlet 71 and the ceramic heater 62 acting asa flat platelike heating means. The ceramic heater 62 is inserted into asubstantial center of the heat exchange portion 64 in watertightnesssuch that only one end portion of the ceramic heater 62 having the leadwires 67 is projected from the heat exchange portion 64.

In the heat exchange portion 64, there are provided the inflow path 85extending along one side of the ceramic heater 62 from the water inlet70, the branch portion 81 for effecting branching of the water passageto opposite faces of the ceramic heater 64, which is provided downstreamof the inflow path 85, a pair of the meandering water passages 69 whichare disposed at the opposite faces of the ceramic heater 62 and open tothe ceramic heater 62 so as to bring water into direct contact with theceramic heater 62, the confluent portion 83 for causing confluence ofthe two meandering water passages 69 at their terminal ends and theoutflow path 86 for guiding hot water from the confluent portion 83 tothe hot water outlet 71, which is provided at the other side of theceramic heater 62 opposite to the in flow path 85. Meanwhile, the waterheater body 61 is fixed such that the ceramic heater 62 standssubstantially vertically. The water inlet 70 is disposed at a lowermostlocation of the ceramic heater 62, while the inflow path 85, the branchportion 81, the meandering water passage 69, the confluent portion 83and the outflow path 86 are disposed gradually more upwardly in anupstream direction in this sequence and thus, the hot water outlet 71 isdisposed at an uppermost location of the ceramic heater 62. Themeandering water passage 69 is also arranged to prevent downstream sideof the meandering water passage 69 from flowing downwardly.

By the above described arrangement, since the ceramic heater 62 having ahigh temperature raise speed and made of alumina which is an electricalinsulator and has a large thermal conductivity transfers heat to waterwhile being in direct contact with water, temperature raise andtemperature control response of hot water can be performed in a momentand thermal efficiency can be improved. Meanwhile, since water flow isdirected sequentially upwardly from the water inlet 70 to the hot wateroutlet 71 via the meandering water passage 69, air bubbles produced byseparation of dissolved oxygen, etc. due to rise of water temperatureare carried to the hot water outlet 71 by buoyancy so as to bedischarged therefrom. Therefore, since turbulence due to air bubbles isnot produced in flow of discharged hot water, the water heater can beoperated safely by maintaining steady discharge of hot water. Moreover,it is. possible to prevent drop of heat transfer rate and thermalefficiency due to air bubbles in the heat exchange portion 64.Furthermore, since such a phenomenon is eliminated that air bubblesformed integrally to larger diameter remain at a spot in the meanderingwater passage 69 so as to cause local heat shock upon sudden drop ofheat transfer rate at the spot, excessive reduction of service life ofthe ceramic heater 62 due to its fracture, etc. is prevented and thus,reliability of the flat platelike heating means can be improved. Inaddition, since water is caused to flow in parallel along the oppositefaces of the ceramic heater 62, temperature gradient is not producedbetween the opposite faces of the ceramic heater 62, so that fracture ofthe ceramic heater 62 due to thermal strain can be prevented and thus,reliability of the flat platelike heating means can be improved.

(Seventh Embodiment)

FIG. 20 and 21 are a schematic perspective view and a schematic view ofa water heater employed in a human privates washing apparatus accordingto a seventh embodiment of the present invention. Constituent elementshaving reference numerals identical with those of FIGS. 8 to 19correspond to the constituent elements of FIGS. 8 to 19 and therefore,the detailed description is abbreviated. In the drawings, a water supplysource (not shown) and the respective water inlets 70 of a pair of theresinous heat exchange portions 64 are connected with the water supplypipe 82 having the branch portion 81, while the two hot water outlets 71are connected with the hot water discharge pipe 84 having the confluentportion 83. A thermistor 89 for detecting temperature of discharged hotwater is provided at a portion of the hot water discharge pipe 84downstream of the confluent portion 83. The water heater body 61 isfixed such that the ceramic heater 62 stands substantially vertically.Since the meandering water passage 69 communicating with the water inlet70 and the hot water outlet 71 of each of the heat exchange portions 64is formed so as to be directed sequentially upwardly from the waterinlet 70 to the hot water outlet 71, the water inlet 70 is provided at asubstantially lowermost location of the water heater body 61, while thehot water outlet 71 is disposed at a substantially uppermost location ofthe water heater body 61. As a heating element in the ceramic heater 62,heating elements 90 a and 90 b are formed by two circuits of electricheaters having a substantially identical wattage and provided inparallel. One end of each of the two circuits is connected to a commonlead wire 91. Meanwhile, the other end of one of the two circuits isconnected to a lead wire 92 a, while the other end of the other of thetwo circuits is connected to a lead wire 92b. The common lead wire 91and the lead wires 92 a and 92 b are connected to a controller 93 forcontrolling ratios of electric power supplied to the heating elements 90a and 90 b, respectively.

By the above described arrangement, the meandering water passage 69extending sequentially upwardly from the water inlet 70 to the hot wateroutlet 71 is provided. Therefore, even if air bubbles are produced, theair bubbles are carried to the hot water outlet 7l so as to bedischarged therefrom. Accordingly, not only the water heater can beoperated safely by maintaining. steady discharge of hot water but it ispossible to prevent drop of heat transfer rate and thermal efficiencydue to air bubbles in the heat exchange portion 64. Meanwhile, sincelocal heat shock due to air bubbles formed integrally to larger diameteris eliminated, fracture of the ceramic heater 62 is prevented and thus,reliability of the flat platelike heating means can be improved.Furthermore, since water is fed in parallel along the opposite faces ofthe ceramic heater 62, fracture of the ceramic heater 62 due to thermalstrain is prevented and thus, reliability of the flat platelike heatingmeans can be improved. Moreover, since the heating elements 90 a and 90b are formed by the two circuits of the electric heaters having theidentical wattage and provided in parallel, wattage of the electricheater of one circuit is reduced relative to a required total wattage ata rate of an inverse number of the number of circuits. As a result,since ratio of electric power supplied to each circuit having a smallwattage is controlled, control resolution is remarkably improved andelaborate temperature control can be performed and heat shock can belessened, so that service life of the electric heater is lengthened,thus resulting in improvement of its reliability. Meanwhile, in the caseof cycle control method in which the number of cycles is adjusted in acontrol period of a predetermined duration and ratios of electric powersupplied to the electric heaters is controlled by repeating the controlperiod, each electric heater having a small wattage may be turned on andoff cyclically, so that variations of voltage of a power source line canbe restricted small. As a result, flicker of illumination, etc. can beprevented and temperature variations uncomfortable for an user of thewater heater can be restrained.

Meanwhile, in this embodiment, the electric heaters having an identicalwattage are provided in two circuits. However, if the number of thecircuits is increased further, control resolution is further improvedand thus, similar effects can be gained. Meanwhile, even if the electricheaters do not have a substantially identical wattage, similar effectscan be apparently achieved by a control method.

(Eighth Embodiment)

FIG. 22 is an enlarged fragmentary sectional view of a water heateremployed in a water heater according to an eighth embodiment of thepresent invention. In FIG. 22, the meandering water passage 69 has arectangular cross section and a twisted plate 94 acting as a turbulentflow generator is inserted into the meandering water passage 69. In theabove described arrangement, main flow of water flowing in themeandering water passage 69 is turned by action of the twisted plate 94,so that heat transfer rate from a wall surface of the meandering waterpassage 69 to water is improved. Hence, since heat transfer area can bereduced, the water heater can be made for higher load and more compact.

(Ninth Embodiment)

FIG. 23 is an enlarged fragmentary sectional view of a water heateremployed in a human privates washing apparatus according to a ninthembodiment of the present invention. In FIG. 23, the meandering waterpassage 69 has a rectangular cross section and a coiled wire 95 wound ina rectangular form and acting as a turbulent flow generator is insertedinto the meandering water passage 69.

In the above described arrangement, flow of water flowing in themeandering water passage 69 is agitated in the vicinity of a heattransfer surface by action of the wire 95, so that heat transfer ratefrom a wall surface of the meandering water passage 69 to water isimproved. Therefore, since heat transfer area can be reduced, the waterheater can be made for higher load and more compact.

Meanwhile, in the eighth and ninth embodiments, the twisted plate 94 andthe wire 95 are employed as the turbulent flow generators but may bereplaced by a rectangular, trapezoidal, saw-toothed or triangularprojection which is provided on the heat transfer surface so as toagitate flow in the vicinity of the heat transfer surface, a spiral vanefor turning main flow or circular plates or rings which are arranged atregular intervals on a conduit so as to agitate main flow.

(Tenth Embodiment)

FIGS. 24 and 25 are a sectional view and a front elevational view of aflow rate sensor 105 employed in a human privates washing apparatusaccording to a tenth embodiment of the present invention, respectively.In FIGS. 24 and 25, a housing 106 is made of transparent material andhas therein a substantially cylindrical chamber 107 connected with aninflow path 108 and an outflow path 109. In the chamber 107, a rotor 111having six rotary vanes 110 extending radially from its axis at regularangular intervals and having an identical shape is rotatably supportedby a shaft 112 provided substantially at a cylindrical center of thechamber 107 and is arranged to be rotated by fluidal force exerted byfluid having entered from the inflow path 108. Meanwhile, the inflowpath 108 is parallel to a tangent of a rotational circle defined by therotor 111 and is disposed at a location spaced a predetermined distancefrom an outer periphery of the rotary circle towards the shaft 112. Theoutflow path 109 opens to such a position that fluid entering from theinflow path 108 draws a substantially U-shaped streamline as shown bythe arrow in FIG. 25. Meanwhile, a photo interrupter 113 acting as ameans for detecting the number of revolutions is provided on the housing106. In the photo interrupter 113, a light emitting diode 114 acting asa light emitting element and a photo diode 115 acting as a photosensorconfront each other so as to have an optical axis parallel to the shaft112.

Operation of the flow rate sensor 105 of the above described arrangementis described. Initially, fluid entering from the inflow path 108 iscurved along the shape of the chamber 107 and flows by drawing thesubstantially U-shaped streamline as shown by the arrow in FIG. 25 so asto be discharged from the outflow path 109. Since the rotor 111 havingthe six rotary vanes 110 is rotatably supported by the shaft 112 in thechamber 107 at this time, fluid exerts fluidal force on the rotary vanes110 so as to counterclockwise rotate the rotor 111 about the shaft 112in FIG. 25. Since fluid exerts fluidal force on a plurality of therotary vanes 110 at all times even if rotational angular position of therotor 111 changes, scatter of rotational force applied to the rotor 111as a whole is reduced and thus, the rotor 111 is rotated stably at alltimes. Meanwhile, since a plurality of the rotary vanes 110 aresubjected to fluidal force, rotational force is increased and thus, therotor 111 can be rotated even at a minute flow rate.

Meanwhile, light irradiated from the light emitting diode 114 istransmitted through the transparent housing 106 and reaches the photodiode 115 provided at an opposed position. At the time the rotary vanes110 pass across the optical axis, light is intercepted by a thickness ofeach of the rotary vanes 110 in a tangential direction of the rotationalcircle of the rotor 111, so that output of the photo diode 115 changesand thus, the number of revolutions of the rotor 111 is detected bycounting these output changes. Meanwhile, since the six votary vanes 110are provided, six output changes of the photo diode 115 are countedduring one rotation of the rotor 111, so that minute changes of flowrate, etc. can be detected positively and thus, accuracy of detection offlow rate is improved greatly.

By the arrangement of this embodiment, since fluid entering from theinflow path 108 is discharged from the outflow path 108 via therotational circle of the rotor 111 so as to draw the substantiallyU-shaped streamline, the rotor 111 is subjected to large fluidal force.Therefore, since the rotor 111 is rotated even at a minute flow rate andis rotated uniformly and stably, minute flow rate can be detected highlyaccurately. Meanwhile, since a center of gravity of the rotor 111coincides with the shaft 112, scatter of rotational force of the rotor111 according to rotational angular position of the rotor 111 isreduced, so that the rotor 111 is rotated smoothly and positively andthus, minute flow rate can be detected highly accurately. Furthermore,since the rotor 111 has a quite simple construction, resistance torotation of the rotor 111 is small and adhesion of air bubbles theretocan be prevented. In addition, even if air bubbles adhere to the rotor111, the air bubbles can be readily separated therefrom. As a result,the rotor 111 can be rotated smoothly and positively.

(Eleventh Embodiment)

FIGS. 26 and 27 are a sectional view and a front elevational view of aflow rate sensor 116 employed in a human privates washing apparatusaccording to an eleventh embodiment of the present invention,respectively. In FIGS. 26 and 27, a housing 117 is made of transparentmaterial and has therein a substantially cylindrical chamber 118connected with an inflow path 119 and an outflow path 120. In thechamber 118, a rotor 122 having six rotary vanes 121 extending radiallyfrom its axis at regular angular intervals and having an identical shapeis rotatably supported by a shaft 123 and is arranged to be rotated byfluidal force exerted by fluid having entered from the inflow path 119.Meanwhile, a pair of bosses 124 are provided around the axis of therotor 122. When the rotor 122 is displaced leftwards or rightwards inFIG. 26, the bosses 124 are brought into contact with the housing 117such that the rotary vanes 121 do not come into direct contact with thehousing 117. Furthermore, the inflow path 119 is parallel to a tangentof a rotational circle defined by the rotor 122 and is disposed at alocation spaced a predetermined distance from an outer periphery of therotary circle towards the shaft 123. In addition, the outflow path 120is provided such that fluid entering from the inflow path 119 isdischarged in parallel with the shaft 123 inwardly of the outerperiphery of the rotational circle of the rotor 122, i.e., at one sideof the outer periphery of the rotational circle of the rotor 122adjacent to the shaft 123. Meanwhile, a photo interrupter 125 acting asa means for detecting the number of revolutions is provided on thehousing 117. In the photo interrupter 125, a light emitting diode 126acting as a light emitting element and a photo diode 127 acting as aphotosensor confront each other so as to have an optical axis parallelto the shaft 123. Moreover, a temperature thermistor 128 and anarithmetic unit 129 which act as output correcting means are provided inthe course of the inflow path 119 such that output of the photointerrupter 125 is corrected in accordance with output of thetemperature thermistor 128.

Operation of the flow rate sensor 116 of the above described arrangementis described. Initially, fluid entering from the inflow path 119 iscurved along the shape of the chamber 118 and flows by drawing asubstantially U-shaped streamline as shown by the arrow in FIG. 27.Then, the fluid is discharged in parallel with the shaft 123 inwardly ofthe outer periphery of the rotational circle of the rotor 122, i.e., atone side of the outer periphery of the rotational circle of the rotor122 adjacent to the shaft 123. Since the rotor 122 having the six rotaryvanes 121 is rotatably supported by the shaft 123 in the chamber 118 atthis time, fluid exerts fluidal force on the rotary vanes 121 so as toclockwise rotate the rotor 122 about the shaft 123 in FIG. 27. Sincefluid exerts fluidal force on a plurality of the rotary vanes 121 at alltimes even if rotational angular position of the rotor 122 changes,scatter of rotational force applied to the rotor 122 as a whole isreduced and thus, the rotor 122 is rotated stably at all times.Meanwhile, since a plurality of the rotary vanes 121 are subjected tofluidal force, rotational force is increased and thus, the rotor 122 canbe rotated even at a minute flow rate. In addition, if air bubblesadhere to the rotary vanes 121 provided on the rotor 122, such a problemmight arise that since the air bubbles are thrust to base portions ofthe rotary vanes 121 by centrifugal force of rotation of the rotor 122,it is difficult to discharge the air bubbles. However, in thisembodiment, since the outflow path 120 is provided in parallel with theshaft 123 and inwardly of the rotational circle of the rotor 122, i.e.,at one side of the rotational circle of the rotor 122 adjacent to theshaft 123, the air bubbles are readily discharged without remaining onthe rotor 122 for a long time.

Meanwhile, light irradiated from the light emitting diode 126 istransmitted through the transparent housing 117 and reaches the photodiode 127 provided at an opposed position. At the time the rotary vanes121 pass across the optical axis, light is intercepted by a thickness ofeach of the rotary vanes 121 in a tangential direction of the rotationalcircle of the rotor 122, so that output of the photo diode 127 changesand thus, the number of revolutions of the rotor 122 is detected bycounting these output changes. Meanwhile, since the six votary vanes 121are provided, six output changes of the photo diode 127 are countedduring one rotation of the rotor 122, so that minute changes of flowrate, etc. can be detected positively and thus, accuracy of detection offlow rate is improved greatly. Furthermore, if temperature of fluidchanges, the number of revolutions of the rotor 122 changes upon changeof viscosity of fluid. However, the arithmetic unit 129 corrects thiserror in accordance with output of the temperature thermistor 128 s0 asto output accurate signals of flow rate.

By the arrangement of this embodiment, since fluid entering from theinflow path 119 is discharged from the outflow path 120 through therotational circle of the rotor 122 so as to draw the substantiallyU-shaped streamline, the rotor 122 is subjected to large fluidal force.Therefore, since the rotor 122 is rotated even at a minute flow rate andis rotated uniformly and stably, minute flow rate can be detected highlyaccurately. Meanwhile, since the outflow path 120 is provided inparallel with the shaft 123 and inwardly of the rotational circle of therotor 122, i.e., at one side of the rotational circle of the rotor 122adjacent to the shaft 123, air bubbles are readily discharged withoutremaining on the rotor 122 for a long time, so that rotationalnonuniformity of the rotor 122 due to adhesion of air bubbles thereto islessened and thus, the rotor 122 can be rotated smoothly and positively.In addition, since the bosses 124 are provided around the axis of therotor 122, the rotary vanes 121 are not brought into direct contact withthe housing 117 even if the rotor 122 is displaced laterally in FIG. 26,resistance to rotation of the rotor 122 can be reduced greatly.Meanwhile, since the arithmetic unit 129 corrects output of the photointerrupter 125 in accordance with output of the temperature thermistor128, it is possible to perform accurate detection of flow rate havinglittle error due to temperature change of fluid.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom. Industrial Applicability

In the human privates washing apparatus according to the firstembodiment of the present invention, the following effects can begained.

(1) Since amount of air mixed into wash water is changed in response tocontrol of flow rate of wash water, it is possible to prevent retentionof air at the heating means or the hot water pipe and deterioration ofbodily sensation and washing capability, which are caused by improperair mixing ratio. Meanwhile, since the user need not perform a pluralityof operations, operation is made simple and convenient. Since loss dueto heat dissipation is lessened by heating wash water by theinstantaneous heating type heating means only in case of necessity andamount of wash water is reduced by mixing air thereinto, powerconsumption is reduced greatly.

(2) Since air mixing amount is controlled in accordance with flow ratedetected by the flow rate detecting means for detecting amount of washwater, ratio of amount of air mixed into wash water to amount of thewash water can be set properly and the air mixing means can be stoppedin response to suspension of water supply, etc. Therefore, it ispossible to prevent local boiling or abnormal heating due to flow of airinto the heating means.

(3) Since proper setting of ratio of amount of air mixed into wash waterto amount of the wash water and operation of the heating means areperformed in accordance with flow rate detected by the flow ratedetecting means, ratio of amount of air mixed into wash water to amountof the wash water can be set properly and the air mixing means can bestopped in response to suspension of water supply, etc., so that it ispossible to prevent local boiling or abnormal heating due to flow of airinto the heating means. In addition, by controlling the heating means byconfirming that wash water is flowing positively, it is possible toprevent damage to the heating means even during long suspension of watersupply.

(4) If the washing setting means is used without especially adding theflow rate detecting means structurally, the air mixing means and theheating means can be controlled in association with each other by onlysetting of the washing setting means. Furthermore, since it is possibleto cope with a case in which the air mixing means and the heating meansshould be controlled immediately at the time of stop of supply of washwater, etc., late heating caused by residual heat and abnormal heatingcan be prevented.

(5) Since ratio of amount of air mixed into wash water is reduced by theair mixing means as amount of the wash water is reduced by the watersupply controlling means, such a phenomenon can be prevented that airbubbles become larger in diameter at the time of reduction of amount ofthe wash water due to drop of internal pressure of the hot water pipeleading to the discharge means. Hence, it is possible to preventdeterioration of bodily sensation.

(6) Since ratio of amount of air mixed into wash water is increased bythe air mixing means as amount of the wash water is reduced by the watersupply controlling means, it is possible to deal with a use in whichstimulative sensation is desired especially at low flow rate. Moreover,further saving of water and further reduction of power consumption canbe achieved.

(7) By changing ratio of amount of air mixed into wash water to amountof the wash water through selection by the selection means, washingcapability corresponding to not only preference of bodily sensationvariable according to sites of the privates but purposes for use can beselected, thereby resulting in promotion of the user's convenience.

(8) Since air from the air mixing means is mixed into hot water betweenthe heating means and the washing nozzle, it is possible to preventlocal boiling and abnormal heating which are caused by retention of airbubbles in the heating means. Meanwhile, it is possible to prevent notonly such a phenomenon that air bubbles mixed into water are formedintegrally to larger diameter and give intermittent sensation to theuser when injected from the washing nozzle but scattering of hot washwater. Furthermore, since the heating means is of instantaneous heatingtype, water may be heated only when washing is needed, so that loss dueto heat dissipation can be reduced and thus, power consumption can belessened.

(9) By performing heating by the heating means only when flow of wateror hot water has been detected by the flow rate detecting means, it ispossible to secure safety and reliability of the apparatus in the casewhere a large amount of air has been supplied or water supply has beensuspended.

(10) Since the controller causes the water supply controlling means tostop water supply if temperature detected by the temperature detectingmeans has exceeded the predetermined value, it becomes possible to stopsupply of high-temperature water in the case where-temperature of hotwater has exceeded the predetermined value at the time of failure of aheating control system of the heater or drop of flow rate, so thatsafety can be secured in the case of malfunctioning.

(11) By heating the heating means itself by the heating means whenwashing is not being performed, it becomes possible at the time ofwashing to supply in a short period hot water having a desiredtemperature. If heating is not performed by the heating means whenpresence of air is detected by the air detecting means, heating is notperformed without water, thereby resulting in greater safety of theapparatus.

(12) By providing the selection means for performing heating by theheating means when water or hot water is not flowing, the user canarbitrarily select heating by the heating means when water or hot wateris not flowing, thus resulting in improvement of operationalconvenience.

(13) By detecting proximity of the user to the toilet seat by theproximity detecting means so as to perform heating by the heating meanswhen washing is not performed, selection can be made without the needfor the user's additional operation, so that unnecessary preheating isprevented and operating efficiency is improved further.

Meanwhile, the water heaters of the human privates washing apparatusesaccording to the second to ninth embodiments of the present inventionhave the following effects.

(1) Since the water heater includes the flat platelike heating means,the water inlet for receiving water, the hot water outlet fordischarging hot water heated by the flat platelike heating means and themeandering water passage which is communicated with the water inlet andthe hot water outlet, has at least one bent portion and is disposed inthermal contact with the flat platelike heating means, hot water havinga fixed temperature can be discharged for a long time by theinstantaneous heating type water heater.

Meanwhile, since flow velocity and heat transfer rate can be increasedby reducing cross-sectional area of the meandering water passage whileheat transfer area is secured, the water heater can be made for higherload and more compact at high thermal efficiency and in simpleconstruction. Furthermore, since the water storage portion is notprovided, the water heater has high temperature raise speed and moreexcellent control response.

(2) Since the flat platelike heating means is formed by the ceramicheater in which the heating element producing Joule's heat by supplyingelectric power thereto is gripped between a pair of the ceramic platesmade of alumina or the like, the ceramic heater is formed by aluminawhich is an electrical insulator and has a large thermal conductivity,so that temperature raise speed of the flat platelike heating meansitself is high. As a result, since temperature raise and temperaturecontrol response of hot water can be performed in a moment and themeandering water passage may be arranged such that water is brought intodirect contact with the ceramic heater, temperature raise speed andresponse can be improved further and thermal efficiency also can beimproved.

(3) Since the fuel passage for passing therethrough fuel such ashydrocarbon fuel and the catalytic combustion portion for oxidizing thefuel so as to produce heat therefrom are provided between the flatplates in the flat platelike heating means, it is possible tomaterialize the instantaneous heating type compact water heater having asimple construction and employing the fuel such as the hydrocarbon fuel.Since catalytic combustion is employed, the water heater emits cleanexhaust gas without producing nitrogen oxides.

(4) Since the resinous heat exchange portion having the meandering waterpassage is provided, thermal capacity of the heat exchange portion islessened, so that thermal capacity of the water heater as a whole is notincreased and thus, temperature raise speed and temperature controlresponse of hot water can be improved.

(5) Since the meandering water passage is provided with the water inletand the hot water outlet and the inflow path adjacent to the water inletand the outflow path adjacent to the hot water outlet are provided nextto each other in the meandering water passage, heat exchange isperformed by temperature difference also between the inflow path and theoutflow path, so that temperature difference in the meandering waterpassage is mitigated and thus, distribution of temperature over the heattransfer faces of the flat platelike heating means is made more uniform.As a result, fracture of the ceramic heater due to thermal strain can beprevented.

(6) Since the flat platelike heating means is disposed substantiallyvertically and the water inlet and the hot water outlet are,respectively, provided at the substantially lowermost end and thesubstantially uppermost end of the meandering water passage, themeandering water passage is directed sequentially upwardly from thewater inlet to the hot water outlet. Therefore, even if air bubbles areproduced through separation of dissolved oxygen from water upon rise oftemperature of the water, the air bubbles are carried to the hot wateroutlet by buoyancy so as to be discharged from the hot water outlet, sothat hot water is discharged steadily without turbulence in flow of thedischarged hot water due to the air bubbles such that the water heatercan be operated safely. In addition, it is possible to prevent drop ofheat transfer rate due to the air bubbles in the water heater and dropof thermal efficiency.

Furthermore, since such a phenomenon is eliminated that air bubblesformed integrally to larger diameter remain at a spot in the meanderingwater passage and heat transfer rate drops suddenly at the spot so as tocause local heat shock, safety of the flat platelike heating means canbe improved.

(7) Since the meandering water passage extends beyond the outer boundaryof the heating portion of the flat platelike heating means, the waterpassage is present over a range wider than that of the heating portionof the flat platelike heating means. Therefore, since such a phenomenonis prevented that heat flow is transferred to the constituent members ofthe water heater without being absorbed by water and a portion, forexample, an end portion of the water heater reaches abnormally hightemperature, thermal efficiency and safety can be improved.

(8) Since the branch portion disposed upstream of the meandering waterpassage and the confluent portion disposed downstream of the meanderingwater passage are provided and water is caused to flow through themeandering water passages on the opposite faces of the flat platelikeheating means, temperature gradient is not produced between the oppositefaces of the flat platelike heating means and warpage or fracture of theflat platelike heating means due to thermal strain is prevented, therebyresulting in improvement of safety.

(9) The heat transfer plate having a large thermal conductivity isprovided between the flat platelike heating means and the meanderingwater passage. Therefore, even if gradient distribution of temperatureis produced in a plane between the meandering water passage and the heattransfer plate by water flow, the gradient distribution of temperatureis, before being transferred to the surface of the flat platelikeheating means, mitigated by the heat transfer plate having the largethermal conductivity, so that distribution of temperature on the surfaceof the flat platelike heating means is made more uniform and thus,fracture of the ceramic heater due to thermal strain can be prevented.

(10) Since the water heater includes the flat platelike heating means inwhich the electric heaters of two or more circuits connected in parallelare provided in one flat plate, the temperature detecting means fordetecting temperature of discharged hot water and the controller forcontrolling ratios of electric power supplied to the electric heaters,the electric heaters are formed by a plurality of the circuits connectedin parallel, so that wattage of the electric heater per circuit isreduced. As a result, since ratio of electric power supplied to eachcircuit having the small wattage is controlled, control resolution isimproved remarkably so as to enable elaborate temperature control andheat shock is also reduced, so that reliability of the electric heatercan be improved by lengthening its service life. Meanwhile, in casecycle control method is employed in which the number of cycles isadjusted in a control period of a fixed duration and ratios of electricpower supplied to the electric heaters is controlled by repeating thecontrol period, each electric heater having the small wattage may beturned on and off cyclically, so that variations of voltage of the powersource line can be restricted small. As a result, flicker ofillumination, etc. can be prevented and temperature variationsuncomfortable for the user of the water heater can be restrained.

(11) Since the turbulent flow generator is provided in the meanderingwater passage, heat transfer rate from the flat platelike heating meansto water can be improved by the turbulent flow generator, so that heattransfer area can be lessened and thus, the water heater can be made forhigher load and more compact by using the flat platelike heating meanshaving large watt density.

Furthermore, the flow rate sensors of the human privates washingapparatuses according to the tenth and eleventh embodiments have thefollowing effects.

(1) Since fluid entering from the inflow path is discharged from theoutflow path by drawing the substantially U-shaped streamline along therotational circle of the rotor, the rotor is subjected to large fluidalforce and thus, can be rotated even at minute flow rate. Since thenumber of revolutions is detected by the means for detecting the numberof revolutions, minute flow rate can be detected highly accurately.

(2) Since not only the center of gravity of the rotary vanes coincideswith the axis of the rotor but a plurality of the rotary vanes arearranged at the regular angular intervals, scatter of rotational forceaccording to rotational angular position of the rotor is small.Furthermore, since fluid entering from the inflow path exerts fluidalforce on the rotary vanes positively, the rotor is rotated smoothly andpositively and thus, minute flow rate can be detected highly accurately.

(3) Since the rotor has a simple construction, resistance to rotation ofthe rotor is small. Meanwhile, since adhesion of air bubbles to therotary vanes can be prevented and air bubbles adhering to the rotaryvanes can be readily separated from the rotary vanes, the rotor can berotated smoothly and positively and thus, minute flow rate can bedetected highly accurately.

(4) Since the outflow path is provided in parallel with the axialdirection of the rotor, air bubbles adhering to the rotary vanes of therotor are readily discharged without being thrust towards the axis ofthe rotor, so that rotational nonuniformity of the rotor due to adhesionof air bubbles thereto is lessened and thus, minute flow rate can bedetected highly accurately.

(5) The outflow path is provided at one side of the outer periphery ofthe rotor adjacent to its axis. Therefore, also when bubbles adhere tovicinity of the axis of the rotor, the air bubbles are readilydischarged, so that rotational nonuniformity of the rotor due toadhesion of the air bubbles thereto is reduced and thus, minute flowrate can be detected highly accurately.

(6) The bosses are provided around the axis of the rotor. Therefore,when the rotor is rotated while being depressed in one of opposite axialdirections, frictional resistance of the housing relative to the rotoris minimized, so that the rotor is rotated smoothly and positively andthus, minute flow rate can be detected highly accurately.

(7) since the temperature thermistor detects temperature of fluid andthe arithmetic unit corrects output of the means for detecting thenumber of revolutions, flow rate can be detected highly accuratelyindependently of temperature of fluid.

We claim:
 1. An apparatus for washing human privates, said apparatuscomprising: a water heater which is connected with a water supply pipeand a hot water pipe; a water supply controlling means for controllingsupply of the wash water to the water heater; a discharge means fordischarging to the human privates the wash water heated to a propertemperature by the water heater, which is connected with the hot waterpipe; an air mixing means for mixing air into the wash water; acontroller for controlling so as to change, in response to control ofthe supply of the wash water by the water supply controlling means, anamount of the air mixed into the wash water by the air mixing means,wherein, at the time of use of the wash water, the water heater heatsthe wash water to the proper temperature during flow of the wash waterfrom the supply pipe to the hot water pipe; a flow rate detecting meansfor detecting a flow rate of the wash water, wherein the controllercontrols operation of the water heater in accordance with the flow ratedetected by the flow rate detecting means, wherein the flow ratedetecting means comprises a rotor which includes a plurality of rotaryvanes extending radially from its axis at regular angular intervals andhaving an identical shape, a housing which has a substantiallycylindrical chamber for receiving the rotor, an inflow path which causesthe wash water to flow into the chamber in a tangential direction of arotational circle of the rotor, an outflow path which is provided atsuch a position that a streamline drawn by the wash water flowing intothe chamber from the inflow path defines a substantially U-shaped locusalong the rotational circle of the rotor, and a detection means fordetecting the number of revolutions of the rotor, wherein the detectionmeans includes a light emitting element and a photosensor, and the lightemitting element and the photosensor have an optical axis parallel tothe axis of the rotor such that interceptions of light between the lightemitting element and the photosensor by a thickness of each of therotary vanes in the tangential direction of the rotational circle of therotor are counted by the light emitting element and the photosensor. 2.An apparatus as claimed in claim 1, wherein a boss is provided in thevicinity of the axis of the rotor and the outflow path is formed inparallel with the axis of the rotor and inwardly of an outer peripheryof the rotor.
 3. An apparatus as claimed in claim 1, wherein the flowrate detecting means is provided upstream of the water heater.
 4. Anapparatus for washing human privates, said apparatus comprising: a waterheater which is connected with a water supply pipe and a hot water pipe;a water supply controlling means for controlling supply of the washwater to the water heater; a discharge means for discharging to thehuman privates the wash water heated to a proper temperature by thewater heater, which is connected with the hot water pipe; an air mixingmeans for mixing air into the wash water; a controller for controllingso as to change, in response to control of the supply of the wash waterby the water supply controlling means, an amount of the air mixed intothe wash water by the air mixing means, wherein, at the time of use ofthe wash water, the water heater heats the wash water to the propertemperature during flow of the wash water from the supply pipe to thehot water pipe; and a flow rate detecting means for detecting a flowrate of the wash water, wherein the controller controls operation of thewater heater in accordance with the flow rate detected by the flow ratedetecting means, wherein the flow rate detecting means comprises a rotorwhich includes a plurality of rotary vanes extending radially from itsaxis at regular angular intervals and having an identical shape, ahousing which has a substantially cylindrical chamber for receiving therotor, an inflow path which causes the wash water to flow into thechamber in a tangential direction of a rotational circle of the rotor,an outflow path which is provided at such a position that a streamlinedrawn by the wash water flowing into the chamber from the inflow pathdefines a substantially U-shaped locus along the rotational circle ofthe rotor, and a detection means for detecting the number of revolutionsof the rotor, wherein a boss is provided in the vicinity of the axis ofthe rotor and the outflow path is formed in parallel with the axis ofthe rotor and inwardly of an outer periphery of the rotor.
 5. Anapparatus as claimed in claim 4, wherein the flow rate detecting meansis provided upstream of the water heater.
 6. An apparatus for washinghuman privates, said apparatus comprising: a water heater which isconnected with a water supply pipe and a hot water pipe; a water supplycontrolling means for controlling supply of the wash water to the waterheater; a discharge means for discharging to the human privates the washwater heated to a proper temperature by the water heater, which isconnected with the hot water pipe; an air mixing means for mixing airinto the wash water; a controller for controlling so as to change, inresponse to control of the supply of the wash water by the water supplycontrolling means, an amount of the air mixed into the wash water by theair mixing means, wherein, at the time of use of the wash water, thewater heater heats the wash water to the proper temperature during flowof the wash water from the supply pipe to the hot water pipe; and a flowrate detecting means for detecting a flow rate of the wash water,wherein the controller controls operation of the water heater inaccordance with the flow rate detected by the flow rate detecting means,wherein the flow rate detecting means comprises a rotor which includes aplurality of rotary vanes extending radially from its axis at regularangular intervals and having an identical shape, a housing which has asubstantially cylindrical chamber for receiving the rotor, an inflowpath which causes the wash water to flow into the chamber in atangential direction of a rotational circle of the rotor, an outflowpath which is provided at such a position that a streamline drawn by thewash water flowing into the chamber from the inflow path defines asubstantially U-shaped locus along the rotational circle of the rotor,and a detection means for detecting the number of revolutions of therotor, wherein the flow rate detecting means is provided upstream of thewater heater.
 7. An apparatus for washing human privates, said apparatuscomprising: a water heater which is connected with a water supply pipeand a hot water pipe; a water supply controlling means for controllingsupply of the wash water to the water heater; a discharge means fordischarging to the human privates the wash water heated to a propertemperature by the water heater, which is connected with the hot waterpipe; an air mixing means for mixing air into the wash water; and acontroller for controlling so as to change, in response to control ofthe supply of the wash water by the water supply controlling means, anamount of the air mixed into the wash water by the air mixing means,wherein, at the time of use of the wash water, the water heater heatsthe wash water to the proper temperature during flow of the wash waterfrom the supply pipe to the hot water pipe, wherein the water heaterincludes a flat platelike heating means, a water inlet, a hot wateroutlet and an internal flow path which is communicated with the waterinlet and the hot water outlet, has at least one bent portion and isdisposed in thermal contact with each of opposite faces of the heatingmeans, wherein the heating means is formed by a ceramic heater in whicha heating element producing Joule's heat by supplying electric powerthereto is gripped between a pair of ceramic plates made of alumina orthe like, wherein the water heater includes a heat exchange portionhaving the internal flow path and made of resinous material.
 8. Anapparatus for washing human privates, said apparatus comprising: a waterheater which is connected with a water supply pipe and a hot water pipe;a water supply controlling means for controlling supply of the washwater to the water heater; a discharge means for discharging to thehuman privates the wash water heated to a proper temperature by thewater heater, which is connected with the hot water pipe; an air mixingmeans for mixing air into the wash water; and a controller forcontrolling so as to change, in response to control of the supply of thewash water by the water supply controlling means, an amount of the airmixed into the wash water by the air mixing means, wherein, at the timeof use of the wash water, the water heater heats the wash water to theproper temperature during flow of the wash water from the supply pipe tothe hot water pipe, wherein the water heater includes a flat platelikeheating means, a water inlet, a hot water outlet and an internal flowpath which is communicated with the water inlet and the hot wateroutlet, has at least one bent portion and is disposed in thermal contactwith each of opposite faces of the heating means, wherein the heatingmeans is formed by a ceramic heater in which a heating element producingJoule's heat by supplying electric power thereto is gripped between apair of ceramic plates made of alumina or the like, wherein the heatingmeans is disposed substantially vertically and the water inlet and thehot water outlet are, respectively, provided at a substantiallylowermost end and a substantially uppermost end of the internal flowpath.
 9. An apparatus for washing human privates, said apparatuscomprising: a water heater which is connected with a water supply pipeand a hot water pipe; a water supply controlling means for controllingsupply of the wash water to the water heater; a discharge means fordischarging to the human privates the wash water heated to a propertemperature by the water heater, which is connected with the hot waterpipe; an air mixing means for mixing air into the wash water; and acontroller for controlling so as to change, in response to control ofthe supply of the wash water by the water supply controlling means, anamount of the air mixed into the wash water by the air mixing means,wherein, at the time of use of the wash water, the water heater heatsthe wash water to the proper temperature during flow of the wash waterfrom the supply pipe to the hot water pipe, wherein the water heaterincludes a flat platelike heating means, a water inlet, a hot wateroutlet and an internal flow path which is communicated with the waterinlet and the hot water outlet, has at least one bent portion and isdisposed in thermal contact with each of opposite faces of the heatingmeans, wherein the heating means is formed by a ceramic heater in whicha heating element producing Joule's heat by supplying electric powerthereto is gripped between a pair of ceramic plates made of alumina orthe like, wherein the heating means includes at least two electricheaters arranged in parallel.
 10. An apparatus for washing humanprivates, said apparatus comprising: a water heater which is connectedwith a water supply pipe and a hot water pipe; a water supplycontrolling means for controlling supply of the wash water to the waterheater; a discharge means for discharging to the human privates the washwater heated to a proper temperature by the water heater, which isconnected with the hot water pipe; an air mixing means for mixing airinto the wash water; and a controller for controlling so as to change,in response to control of the supply of the wash water by the watersupply controlling means, an amount of the air mixed into the wash waterby the air mixing means, wherein the water heater includes a heatingmeans, a water inlet, a hot water outlet, an internal flow path which iscommunicated with the water inlet and the hot water outlet, has at leastone bent portion and is disposed in thermal contact with each ofopposite faces of the heating means and a heat exchange portion made ofresinous material and heats, at the time of use of the wash water, thewash water to the proper temperature during flow of the wash water fromthe supply pipe to the hot water pipe.
 11. An apparatus as claimed inclaim 10, wherein the heating means is disposed substantially verticallyand the water inlet and the hot water outlet are, respectively, providedat a substantially lowermost end a substantially uppermost end of theinternal flow path.
 12. An apparatus as claimed in claim 10, wherein theheating means includes at least two electric heaters arranged inparallel.
 13. An apparatus for washing human privates, said apparatuscomprising: a water heater which is connected with a water supply pipeand a hot water pipe; a water supply controlling means for controllingsupply of the wash water to the water heater; a discharge means fordischarging to the human privates the wash water heated to a propertemperature by the water heater, which is connected with the hot waterpipe; an air mixing means for mixing air into the wash water; and acontroller for controlling so as to change, in response to control ofthe supply of the wash water by the water supply controlling means, anamount of the air mixed into the wash water by the air mixing means,wherein the water heater includes a heating means, a water inlet, a hotwater outlet and an internal flow path which is communicated with thewater inlet and the hot water outlet, has at least one bent portion andis disposed in thermal contact with each of opposite faces of theheating means, wherein the heating means is disposed substantiallyvertically and the water inlet and the hot water outlet are,respectively, provided at a substantially lowermost end and asubstantially uppermost end of the internal flow path.
 14. An apparatusas claimed in claim 13, wherein the heating means includes at least twoelectric heaters arranged in parallel.
 15. An apparatus for washinghuman privates, said apparatus comprising: a water heater which isconnected with a water supply pipe and a hot water pipe; a water supplycontrolling means for controlling supply of the wash water to the waterheater; a discharge means for discharging to the human privates the washwater heated to a proper temperature by the water heater, which isconnected with the hot water pipe; an air mixing means for mixing airinto the wash water; and a controller for controlling so as to change,in response to control of the supply of the wash water by the watersupply controlling means, an amount of the air mixed into the wash waterby the air mixing means, wherein the water heater includes a heatingmeans, a water inlet, a hot water outlet and an internal flow path whichis communicated with the water inlet and the hot water outlet, has atleast one bent portion and is disposed in thermal contact with each ofopposite faces of the heating means, wherein the heating means includesat least two electric heaters arranged in parallel.